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Platelets or thrombocytes are a component of blood whose function is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm derived from the megakaryocytes of the bone marrow or lung, which then enter the circulation. Platelets are found only in mammals, whereas in other vertebrates, thrombocytes circulate as intact mononuclear cells.
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin.
TAR syndrome is a rare genetic disorder that is characterized by the absence of the radius bone in the forearm and a dramatically reduced platelet count. It is associated with cardiac defects, dysmorphic features, and petechiae. It involves a 1q21 deletion with RMB8A variant on other allele.
Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.
Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition.
Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura or immune thrombocytopenia, is a type of thrombocytopenic purpura characterized by a low platelet count in the absence of other causes, and accompanied by a red-purple rash called purpura. It leads to an increased risk of bleeding. ITP manifests in two distinct clinical syndromes: an acute form observed in children, and chronic conditions observed in adults. The acute form often follows an infection and typically resolves within two months, while chronic immune thrombocytopenia persists for longer than six months and its specific cause is unknown.
Thrombotic thrombocytopenic purpura (TTP) is a blood disorder that results in blood clots forming in small blood vessels throughout the body. This results in a low platelet count, low red blood cells due to their breakdown, and often kidney, heart, and brain dysfunction. Symptoms may include large bruises, fever, weakness, shortness of breath, confusion, and headache. Repeated episodes may occur.
In hematology, thrombocytopenia is a condition characterized by abnormally low levels of platelets in the blood. Low levels of platelets in turn may lead to prolonged or excessive bleeding. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients and a third of surgical patients.
Wiskott–Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia, immune deficiency, and bloody diarrhea. It is also sometimes called the eczema-thrombocytopenia-immunodeficiency syndrome in keeping with Aldrich's original description in 1954. The WAS-related disorders of X-linked thrombocytopenia (XLT) and X-linked congenital neutropenia (XLN) may present with similar but less severe symptoms and are caused by mutations of the same gene.
Plateletpheresis is the process of collecting thrombocytes, more commonly called platelets, a component of blood involved in blood clotting. The term specifically refers to the method of collecting the platelets, which is performed by a device used in blood donation that separates the platelets and returns other portions of the blood to the donor. Platelet transfusion can be a life-saving procedure in preventing or treating serious complications from bleeding and hemorrhage in patients who have disorders manifesting as thrombocytopenia or platelet dysfunction. This process may also be used therapeutically to treat disorders resulting in extraordinarily high platelet counts such as essential thrombocytosis.
Bernard–Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the glycoprotein Ib-IX-V complex (GPIb-IX-V), the receptor for von Willebrand factor. The incidence of BSS is estimated to be less than 1 case per million persons, based on cases reported from Europe, North America, and Japan. BSS is a giant platelet disorder, meaning that it is characterized by abnormally large platelets.
Mean platelet volume (MPV) is a machine-calculated measurement of the average size of platelets found in blood and is typically included in blood tests as part of the CBC. Since the average platelet size is larger when the body is producing increased numbers of platelets, the MPV test results can be used to make inferences about platelet production in bone marrow or platelet destruction problems.
GATA-binding factor 1 or GATA-1 is the founding member of the GATA family of transcription factors. This protein is widely expressed throughout vertebrate species. In humans and mice, it is encoded by the GATA1 and Gata1 genes, respectively. These genes are located on the X chromosome in both species.
Gray platelet syndrome (GPS), or platelet alpha-granule deficiency, is a rare congenital autosomal recessive bleeding disorder caused by a reduction or absence of alpha-granules in blood platelets, and the release of proteins normally contained in these granules into the marrow, causing myelofibrosis. The name derives from the initial observation of gray appearance of platelets with a paucity of granules on blood films from a patient with a lifelong bleeding disorder.
Pseudo gray platelet syndrome was described by Cockbill, Burmester, and Heptinstall (1988) who reported a 25-year-old woman with a history of mild bruising and bleeding. Another case was described in Japan in 2002.
The dysfibrinogenemias consist of three types of fibrinogen disorders in which a critical blood clotting factor, fibrinogen, circulates at normal levels but is dysfunctional. Congenital dysfibrinogenemia is an inherited disorder in which one of the parental genes produces an abnormal fibrinogen. This fibrinogen interferes with normal blood clotting and/or lysis of blood clots. The condition therefore may cause pathological bleeding and/or thrombosis. Acquired dysfibrinogenemia is a non-hereditary disorder in which fibrinogen is dysfunctional due to the presence of liver disease, autoimmune disease, a plasma cell dyscrasias, or certain cancers. It is associated primarily with pathological bleeding. Hereditary fibrinogen Aα-Chain amyloidosis is a sub-category of congenital dysfibrinogenemia in which the dysfunctional fibrinogen does not cause bleeding or thrombosis but rather gradually accumulates in, and disrupts the function of, the kidney.
Giant platelet disorders, also known as macrothrombocytopenia, are rare disorders featuring abnormally large platelets, thrombocytopenia and a tendency to bleeding. Giant platelets cannot stick adequately to injured blood vessel walls, resulting in abnormal bleeding when injured. Giant platelet disorder occurs for inherited diseases like Bernard–Soulier syndrome, gray platelet syndrome and May–Hegglin anomaly.
X-linked thrombocytopenia, also referred to as XLT or thrombocytopenia 1, is an inherited clotting disorder that primarily affects males. It is a WAS-related disorder, meaning it is caused by a mutation in the Wiskott–Aldrich syndrome (WAS) gene, which is located on the short arm of the X chromosome. WAS-related disorders include Wiskott–Aldrich syndrome, XLT, and X-linked congenital neutropenia (XLN). Of the WAS-related disorders, X-linked thrombocytopenia is considered to be the milder phenotype. Between 1 and 10 per million males worldwide are affected with this disorder. Females may be affected with this disorder but this is very rare since females have two X chromosomes and are therefore typically carriers of the mutation.
Factor XII deficiency is a deficiency in the production of factor XII (FXII), a plasma glycoprotein and clotting factor that participates in the coagulation cascade and activates factor XI. FXII appears to be not essential for blood clotting, as individuals with this condition are usually asymptomatic and form blood clots in vivo. FXII deficiency tends to be identified during presurgical laboratory screening for bleeding disorders.
Epstein syndrome is a rare genetic disease characterized by a mutation in the MYH9 gene in nonmuscle myosin. This disease affects the patient's renal system and can result in kidney failure. Epstein syndrome was first discovered in 1972 when two families had similar symptoms to Alport syndrome. Epstein syndrome and other Alport-like disorders were seen to be caused by mutations in the MYH9 gene, however, Epstein syndrome differs as it was more specifically linked to a mutation on the R702 codon on the MYH9 gene. Diseases with mutations on the MYH9 gene also include May–Hegglin anomaly, Sebastian syndrome and Fechtner syndrome.
References
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- 1 2 Naina HV, Nair SC, Harris S, Woodfield G, Rees MI (November 2005). "Harris syndrome - a geographic perspective". J. Thromb. Haemost. 3 (11): 2581–2. doi: 10.1111/j.1538-7836.2005.01601.x . PMID 16241959. S2CID 19289239.
- 1 2 Naina HV, Harris S (2010). "Platelet and red blood cell indices in Harris platelet syndrome". Platelets. 21 (4): 303–6. doi:10.3109/09537101003615402. PMID 20201635. S2CID 27731719.
- ↑ Aslan, Deniz (November 2016). "Harris Platelet Syndrome in Patients of Non-Indian Origin". Journal of Pediatric Hematology/Oncology. 38 (8): e326–e328. doi:10.1097/MPH.0000000000000602. ISSN 1536-3678. PMID 27299593. S2CID 23158036.
- ↑ Neethirajan, Soma Ganesh Raja; Ramesh, Aishwarya; Parameswari, Aruna (February 2021). "Regional Anaesthesia in Harris Platelet Syndrome for Transurethral Resection of Prostate-A Clinical Conundrum or Certitude?". Turkish Journal of Anaesthesiology and Reanimation. 49 (1): 67–69. doi:10.5152/TJAR.2020.90008. ISSN 2667-677X. PMC 7932712 . PMID 33718909.
- ↑ Gohda F, Uchiumi H, Handa H, et al. (2007). "Identification of inherited macrothrombocytopenias based on mean platelet volume among patients diagnosed with idiopathic thrombocytopenia". Thrombosis Research. 119 (6): 741–746. doi:10.1016/j.thromres.2006.06.011. PMID 16916536.
- ↑ Karmakar, Shilpita; Saha, Sutapa; Banerjee, Debasis; Chakrabarti, Abhijit (January 2015). "Differential proteomics study of platelets in asymptomatic constitutional macrothrombocytopenia: altered levels of cytoskeletal proteins". European Journal of Haematology. 94 (1): 43–50. doi:10.1111/ejh.12398. ISSN 0902-4441. PMID 24934967. S2CID 35510495.